We don't have holidays here, but employers are required to provide us with a certain amount of consecutive free hours (which specific number I can't remember) inside voting hours.
That’s fine, except for places in the US (particularly poor urban areas) where you have to wait in line for hours and hours to vote - it would need to accommodate for that
The fact it takes hours upon hours is a problem in an of itself, it probably acts as a deterrent to vote for many. I just checked, in Canada it's 3 mandatory consecutive hours without docking pay or other penalities.
It’s an intentionally designed problem in blue cities that exist in red states. Constant ratfuckery by republicans influencing polling locations.
I don't think there is any federal law. Could be a law in your state.
I was talking as someone not in the US, but who doesn't have a national holiday either.